Devices such as natural gas compressors, air compressors, steam turbines, and gas turbines, include various internal components, such as vanes, stators, blades, diffusers, housings, and combustors though which quantities of air, natural gas, steam, or combusted gas flow. It is important to the proper operation of these devices that these internal components modify the internal flow in the correct way. These modifications include changing the average properties of the flowing medium (such as pressure, temperature, density, velocity, etc.) and/or the profiles and gradients of these properties.
These internal components are designed to change the properties of the flowing medium within the context of the device, i.e., change the properties in respect to internal devices either upstream or downstream of the particular component. For example, the first stage turbine vane of a gas turbine engine receives combusted air from a combustor and provides the combusted air to turbine blades located downstream.
This interaction between internal components is often a function of the radial and circumferential extent of the component's flow path. For example, a turbine vane includes a portion of a flow path near the hub (inner most lower wall) of the vane and the outer diameter (outer most wall) of the vane. It is typical that components such as turbine vanes provide air in velocity and pressure gradients that change from the inner hub to the outer diameter. Further, these property gradients of the gas change circumferentially, i.e., the gradient closest to the trailing edge of the vane can be different than the gradients at a position in between adjacent trailing edges.
As vanes are manufactured, there are times when the trailing edge of the vane is bent manually. Further, it is possible that the trailing edge of the vane, or other geometrical aspects of the vane, is altered as a result of long-term usage. In either of these situations, the gas property gradients from the exit of the vane are altered. However, there may not be suitable test equipment for characterizing the modified gradients. One simple attempt to provide such information involves the use of a protractor with a single inner foil rotatably coupled to the protractor. As air from a tested component flows across this assembly, the angle of the airfoil changes, similar in operation to a weather vane.
What is needed is an improvement in airflow testing that improves the accuracy with which the flow characteristics of the component are determined. The present invention does this in a novel and nonobvious manner.